For telecommunication in aircrafts, so called direct air-to-ground systems are used. Such systems provide a possibility for telecommunication connections from the aircraft to a base station on the ground. The Aircraft has a bidirectional communication link with the base station located on the ground. The radio signal transmitted by the base station in direction towards the aircraft is called the forward link. For the forward link, the transmission can be made more efficient by techniques like beamforming, in which the direction of emission of the radio signal is focussed and directed towards the receiving aircraft. The advantage is that other aircrafts which are located in the outer part of the lobe will receive less interference from such radio signals. The base station can additionally transmit with less power than would be necessary with omnidirectional transmission schemes.
On the contrary, the aircraft changes often its orientation and altitude. Hence, high efforts would be needed to implement a corresponding system into an aircraft in order to improve the reverse link for transmitting signals from the aircraft to the base station in the same way.